Spherical Harmonics
Orthonormal basis,
, for functions on the sphere.
n’th order
harmonics have 2n+1 components.
Rotation = phase shift (same n, different m).
In space coordinates: polynomials of degree n.
S.H. used for BRDFs (Cabral et al.; Westin et al;). (See also
Koenderink and van Doorn.)
